Door closers of the kind to which the present invention relates include a piston or similar member slidable within a door closer body and driven in a door closing direction by a spring within the door closer. The piston is operatively connected to a drive means which responds to the movement of the piston in the door closing direction so as to cause closing movement of an associated door. Typically this is accomplished by means of a rack associated with the piston and pinion gear operatively connected to a lever, which in turn is connected to the door or door frame depending on the mounting location of the door closer. Hydraulic fluid is utilized to dampen the movement of the piston in the door closing direction. Valve means are usually provided to permit adjustment of the dampening effect.
A desirable feature of such door closers is the ability to retain the door in an opened position for a period of time prior to closing so as to permit unhindered passage through the door. This invention relates to a door closer, and more particularly to a delayed action door closer that delays the closing of a door for an adjustably determined period of time once the door has been moved to its fully open position. This invention further relates to the manner in which the above is acomplished; namely, an interdependent hydraulic delayed action speed control system.
It is an object of this invention to provide a delayed action regulating system in a delayed action door closer which may be adjusted to vary the time period in which the door closer delays the closing of a door during a delayed action stage.
It is a further object of this invention to provide an interdependent regulating system which maintains complete control of a door over its entire closing range, even when the delayed action portion of the system is not used.
It is a further object of this invention to provide an interdependent delayed action regulating system in the checking end of a door closer.
It is a further object of this invention to provide a delayed action regulating system in which the delayed action speed cannot be adjusted faster than the main closing speed of a door closer.
It is a further object of this invention to provide a delayed action regulating system which allows a door closer to have a fully adjustable, independent backcheck.
These and further objects are obtained in a door closing device comprising: A fluid filled cylinder; a piston within the cylinder forming a first, second and third chambers and slidable in opposite directions; a gear mechanism connected to the piston and adapted to be further connected to a pivotable door in order to transmit opening and closing movements of the door to the piston and vice versa; a spring or springs forceably biasing the piston in one of its slidable directions; a first valve means, a second valve means, and third valve means which sequentially control the flow of fluid from the first chamber to the second chamber; and a fourth valve means for controlling the fluid from the third chamber to the second chamber.